Torn was a member of the Texas A&M UniversityCorps of Cadets, although he graduated from the University of Texas[7] where he studied acting under Shakespearean professor B. Iden Payne,[8] and was a member of the Alpha Nu chapter of the Sigma Chi fraternity. After graduation, he served in the Military Police in the United States Army.[9] While serving as a 2nd lieutenant at Fort Hood, Texas, Torn was known as something of a likeable rebel by the enlisted men. He got himself into a bit of trouble with his superiors when he left the field maneuver known as Operation Spearhead to go back to the base for a visit home. He was not alone in his attitude toward an exercise that had as its stated purpose the dispersal of the 1st Armored Division during an atomic attack.

After moving to Hollywood, Torn made his film debut in the 1956 film Baby Doll. Torn then studied at the Actors Studio in New York under Lee Strasberg, becoming a prolific stage actor, appearing in the original cast of Tennessee Williams' play Sweet Bird of Youth, and reprising the role in the film and television adaptations. While in New York, Torn introduced his cousin Sissy Spacek to the entertainment business, and helped her enroll in the Actors Studio.[10]

After portraying Judas, betrayer of Jesus, in 1961's epic film King of Kings, Torn appeared as a graduate student with multiple degrees in 1963's television series Channing, and as Roy Kendall in the Breaking Point episode "Millions of Faces." In 1964, Torn appeared as Eddie Sanderson in the episode "The Secret in the Stone" in The Eleventh Hour and in the premiere of The Reporter.

In 1965, in the film The Cincinnati Kid, he played Slade, a corrupt New Orleans millionaire who pressures Steve McQueen during a high-stakes poker game. On television that year, Torn portrayed Colonel Royce in the episode "The Lorelei" of 12 O-Clock High.

Since then, he has been a character actor in numerous films (see Filmography below).

The part of George Hanson in Easy Rider was written for Torn by Terry Southern, but according to Southern's biographer Lee Hill, Torn withdrew from the project after he and co-director Dennis Hopper got into a bitter argument in a New York restaurant (see On-Set Conflicts section below). Jack Nicholson played Hanson instead in a career-launching performance.

In 1988, he ventured into directing with The Telephone. The screenplay was written by Terry Southern and Harry Nilsson and the film was produced by their company Hawkeye. The story, which focused on an unhinged, out-of-work actor, had been written with Robin Williams in mind. After he turned it down, Whoopi Goldberg expressed a strong interest, but when production began, Torn reportedly had to contend with Goldberg constantly digressing and improvising and he had to plead with her to perform takes that stuck to the script.

Goldberg was backed by the studio, who also allowed her to replace Torn's chosen DP, veteran cinematographer John Alonzo, with her then-husband. As a result of the power struggle, Torn, Southern, and Nilsson cut their own version of the film, using the takes that adhered to the script and this was screened at the Sundance Film Festival, but the studio put together a rival version using other takes and it was poorly reviewed when it premiered in January 1988.[12]

In 1991, he portrayed Albert Brooks' character's celestial defense attorney in Defending Your Life. He was a jeweler who murdered his own nephew to steal a winning lottery ticket in an episode of Columbo that year on TV, "Death Hits the Jackpot."

He returned next in 1962 in the play Daughter of Silence as Carlo, following that with a role in the 1963 production of Strange Interlude. In 1964, he played Lyle Britten in Blues for Mister Charlie, and four years later he was Roberto in The Cuban Thing for its only performance on September 24, 1968.

In 1971, he portrayed Edgar in Dance of Death, and directed his first Broadway play in 1973: Look Away. In 1975, he portrayed the Son in the Broadway revival of The Glass Menagerie and 5 years later, portrayed Don in Mixed Couples. For 13 years, Torn was absent from Broadway, but returned in 1993 to portray Chris Christopherson in Anna Christie. In his last Broadway appearance in 1997, Torn portrayed Will Kidder in The Young Man from Atlanta.

Torn's Off-Broadway debut as director was for the Evergreen Theater with the play The Beard; he won the 1968 Obie for Distinguished Direction for that work. He next directed The Honest-to-God Schnozzia at the Gramercy Arts Theater, followed by Strindberg's Creditors and The Stronger – in which he acted beside his wife at the time, Geraldine Page and his future wife, Pasha Dabiri – for the Joseph Papp Public Theater. Torn and Page also co-produced that production, and had previously presented the two plays along with Miss Julie at the Off-Off-Broadway Hudson Guild Theatre the year before.

From 1992 to 1998, Torn portrayed Artie in The Larry Sanders Show. For his work, Torn received 6 consecutive Emmy award nominations as Best Supporting Actor in a Comedy Series and won the award once (1996). Torn was the only actor in the series who won an Emmy Award for his work. Other than the Emmys, he received two American Comedy Awards nominations for Funniest Male Performance in a Series, winning once, and two CableACE Awards for his work on the series.

Following The Larry Sanders Show, Torn has appeared in many comedic roles in films (see Filmography below). He is also known for his voice work and has done voice-overs for many animated films.

In 2007 and 2008, he made 5 guest appearances on 30 Rock as the fictional Chief Executive Officer of General Electric, Don Geiss. He was nominated for an Emmy Award in the category for Outstanding Guest Actor in a Comedy Series, but lost to Tim Conway, who guest starred in the same sitcom. Torn's character was reportedly killed off as a direct result of his 2010 arrest,[14] though Tina Fey denied this in a DVD commentary. Torn voiced the character of Hephaestus in the 2010 video game, God of War III.

In 1963, Torn married Geraldine Page, and they remained married until her death in 1987. They had a daughter, actress Angelica Page, and twin sons: actor Tony Torn, Jon Torn (an assistant professor of Electronic Media and Film at Northern Arizona University[16]). Torn apparently delighted in the fact that the doorbell of their New York townhouse read Torn Page.[17]

Torn married actress Amy Wright in 1989. They have two children, Katie and Claire Torn.[18][19]

On January 29, 2010, he was arrested after breaking into a Litchfield Bancorp branch office in Lakeville, Connecticut, where he maintains a residence. He was charged with carrying a firearm without a permit, carrying a firearm while intoxicated, first-degree burglary, second-degree criminal trespassing and third-degree criminal mischief. The Connecticut State Police said Torn broke into the bank thinking it was his home.[20] At his court appearance his attorney told the judge his client needed help with alcohol abuse and that he could start treatment immediately in New York state. Torn was released on $100,000 bail.[21]

As a condition of his release, Torn had to be evaluated for substance abuse. On August 11, 2010, Torn was denied special probation, which would have allowed his name to be cleared of charges. The judge in the case cited Torn's history of alcohol abuse and the possession of a loaded weapon while intoxicated, which carries a minimum one-year sentence.[22] On December 14, 2010, Torn pleaded guilty to reckless endangerment, criminal trespass, criminal mischief and the illegal carrying of a firearm, and was given a two-and-a-half-year suspended jail sentence, and three years probation.[23][24]

Appearing as an interview subject in Studs Terkel's 1974 oral-history book Working, Torn confessed, "I have certain flaws in my make-up. Something called irascibility. I get angry easily. I get saddened by things easily."[25]

While filming Maidstone (1970), Torn struck director and star Norman Mailer in the head with a hammer.[26][27] With the camera rolling, Mailer bit Torn's ear and they wrestled to the ground. The fight continued until it was broken up by cast and crew members.[26] The fight is featured in the film. Although the scene may have been planned by Torn, the blood shed by both actors was real,[26] and Torn was reportedly outraged by Mailer's direction.[27]

In 1994, he filed a defamation lawsuit against Dennis Hopper over a story Hopper told on The Tonight Show with Jay Leno.[12] Hopper claimed that Torn pulled a knife on him during pre-production of the film Easy Rider (1969). According to Hopper, Torn was originally cast in the film but was replaced with Jack Nicholson after the incident. Torn claimed in his lawsuit that Hopper pulled the knife on him. A trial court judge ruled in Torn's favor and Hopper was ordered to pay $475,000 in compensatory damages but denied Torn's request for punitive damages, ruling Hopper had not acted with malice. Hopper appealed. A California appellate court upheld the ruling for compensatory damages, and reversed the ruling for the punitive damages, requiring Hopper to pay another $475,000.[28][29]